The Cassandra blob data type represents a constant hexadecimal number defined as 0[xX](hex)+ where hex is a hexadecimal character, such as [0-9a-fA-F]. For example, 0xcafe. The maximum theoretical size for a blob is 2 GB. The practical limit on blob size, however, is less than 1 MB. A blob type is suitable for storing a small image or short string.

Blob conversion functions

This example shows how to use bigintAsBlob:

CREATE TABLE bios ( user_name varchar PRIMARY KEY,

   bio blob

 );

INSERT INTO bios (user_name, bio) VALUES ('fred', bigintAsBlob(3));

SELECT * FROM bios;

 user_name | bio

-----------+--------------------

      fred | 0x0000000000000003

      

This example shows how to use blobAsBigInt.

ALTER TABLE bios ADD id bigint;

INSERT INTO bios (user_name, id) VALUES ('fred', blobAsBigint(0x0000000000000003));

SELECT * FROM bios;

 user_name | bio                | id

-----------+--------------------+----

      fred | 0x0000000000000003 |  3

    def test_can_insert_blob_type_as_bytearray(self):

        """

        Tests that blob type in Cassandra maps to bytearray in Python

        """

        s = self.session

        s.execute("CREATE TABLE blobbytes (a ascii PRIMARY KEY, b blob)")

        params = ['key1', bytearray(b'blob1')]

        s.execute("INSERT INTO blobbytes (a, b) VALUES (%s, %s)", params)

        results = s.execute("SELECT * FROM blobbytes")[0]

        for expected, actual in zip(params, results):

            self.assertEqual(expected, actual)

from cassandra.cluster import Cluster

cluster = Cluster(["10.178.209.161"])

session = cluster.connect('my_keyspace')

s = session

s.execute("CREATE TABLE blobbytes (a ascii PRIMARY KEY, b blob)")

params = ['key1', bytearray(b'blob1')]

s.execute("INSERT INTO blobbytes (a, b) VALUES (%s, %s)", params)

results = s.execute("SELECT * FROM blobbytes")[0]

for expected, actual in zip(params, results):

     print (expected, actual)